[R] remove component from list or data frame

Duncan Murdoch murdoch at stats.uwo.ca
Thu Feb 8 19:09:46 CET 2007


On 2/8/2007 12:30 PM, Jason Horn wrote:
> Sorry to ask such a simple question, but I can't find the answer after 
> extensive searching the docs and the web.
> 
> How do you remove a component from a list?  For example say you have:
> 
> lst<-c(5,6,7,8,9)

In R jargon, that's a vector, not a list.
> 
> How do you remove, for example, the third component in the list?

lst[-3] will do it.

> 
> lst[[3]]]<-NULL     generates an error:  "Error: more elements supplied 
> than there are to replace"

The [[ index ]] syntax only works on true lists.
> 
> 
> 
> Also, how do you remove a row from a data frame?  For example, say you 
> have:
> 
> lst1<-c(1,2,3,4,5)
> lst2<-c(6,7,8,9,10)
> frame<-data.frame(lst1,lst2)
> 
> How do you remove, for example, the second row of frame?

Same idea:

frame <- frame[-2, ]

Duncan Murdoch
> 
> Thanks,
> 
> - Jason
> 
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